As is indicated in Japanese Laid-open Patent Application No. 2001-201138, there is a known system including an air conditioner and a storage battery, in which, when a request (demand) for a peak cut is received from an electric power company or the like that supplies electric power to the system from outside, the air conditioner is operated by using the electric power of the storage battery charged during times such as the night so as to ensure the comfort of the user of the air conditioner while complying with the request.
Furthermore, Japanese Laid-open Patent Application No. 2001-201138 discloses that, when the demand cannot be met merely by utilizing the storage battery, the demand is met by reducing the operating capacity of the air conditioner from the operating capacity desired by the user to a capacity that can meet the demand by utilizing the storage battery.